Khalil Mack is a powerful pass rusher. That’s tough to see during OTA sessions that prohibit pads and hard contact, meaning the rookie linebacker’s best tool remains in the shed.

Largely left with technique and agility, Mack still finds ways to shine. Coaches have lauded his talent and work ethic. His veteran peers, who can often be tough to impress, are signing similar praise.

If extremely early indications are worth anything, this kid could be pretty good.

“I see signs,” left tackle Donald Penn said. “In between snaps, he’s in (veteran defensive end) Justin Tuck’s ear. Khalil’s a special athlete. I can tell from some of his moves and the way he can put his foot in the ground and change directions, for him to be doing that at defensive end, he moves like a defensive back. It’s crazy for a guy that size to be doing that.”

The 6-foot-3, 261-pound athlete received high praise before being selected No. 5 overall, and the Raiders are now seeing this talent in real time. It’s been impressive to many, especially with a relatively refined pass-rush ability for a rookie.

“His movements (have been impressive),” free safety Charles Woodson said. “I’ve watched him a couple of times come off the edge, and he’s a guy that can bend at the waist, he can get low. He can get under tackles if he’s going around the edge. He’s quick enough to where he can get a guy in space coming off the edge. He can make movements in or out and go either way, and he seems to be put together pretty well, so we know he has some strength.”

There are several tests left to pass, through training camp and into the regular season. Mack’s teammates believe he’ll pass.

“It’ll be great to see him in action when it really goes down,” Woodson said. “We all have high hopes for him, because he’s only going to make us better as team. I look forward to playing alongside of him.”

Penn says it’s clear Mack is “working his butt off” during this offseason program despite being asked to wear several hats. He’s played strongside linebacker in the base defense, with a lineman’s responsibilities in the nickel.

“When you get a young kid in there like that, that really has that determination to want to be great,” Penn said, “and I think he’s just going to make that front four, that third-down defense, tough on opposing teams.

“He’s going to have a lot of sacks late in the down. He has a motor that’s relentless. As a tackle, you have to stay on him until you hear the whistle or hear the crowd cheer.”